Thiophosphoric acid esters and process for producing them



United States Patent 3,030,404 THIOPHOSPHORIC ACID ESTERS AND PROCESS FOR PRODUCING THEM Gerhard Schradcr, Wuppertal-Cronenberg, Germany, as-

signor to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Filed June 11, 1957, Ser. No. 664,919 Claims priority, application Germany June 29, 1956 4 Claims. (Cl. 260--461) The present invention relates to and has as its objects new and useful thiophosphoric acid esters as well as their preparation. Generally these new esters correspond to the following formula wherein n stands for a whole number up to 4, R stands for hydrogen or a lower alkyl radical, X stands for oxygen or sulfur, at least one X being sulfur, and R and R? stand for lower alkyl radicals.

Many thioand dithiophosphoric acid esters have become known and important insecticides and plant protecting agents recently. A special class of compounds in the group of phosphorus insecticides includes such compounds which have in one of their alkyl ester groups a substituent such as a mercapto group, an amino group, a hydroxy group and the like.

It has now been found that a new and useful class of phosphorus insecticides of the above shown formula may be obtained either by reacting nitroalkanols with 0.0-dialkylthionophosphoric acid halides or by reacting nitroalkyl halides with 0.0-dialkylthio or dithiophosphoric acid salts. The two types of reactions may be demonstrated by the following Equations A and B, in which nitroethanol or nitroethyl chloride or the 0.0-diethylthiophosphoric acid chloride or 0.0-diethylthioor dithio- In case A the reaction generally may becarried out in .the presence .of an inert solvent such as benzene, toluene,

,lower aliphatic 1iquid-hydrocarbons and thelikeQThe presence of an acid-binding agent is advisable and mostly necessary. Such acid-binding agents may be either alkali methyl hydroxides or alcoholates or even better tert.

-organic amines such as pyridine, triethyl amine and the 3,030,404 Patented Apr. 17, 1962 ice intermediate phosphite with sulfur. This reaction may be shown by the following scheme A alkali /PCl H O-CHs-CHz-NOR H5010 sCzO S PO-CHr-CH2NO2 H5020 S \H P-O-CHr-GHr-NO:

When according to B thiolor thionothiol nitroalkyl esters should be prepared the reaction also should be carried out in inert organic solvents. The optional solvents in this case are lower aliphatic alcohols such as ethanol or methanol or lower aliphatic ketones such as V The reaction also proceeds at slightly elevated temperatures, say about 60 to 70 C. to yield optionally the inventive compounds. Especially ammonium salts of thiolor thionothiol phosphoric acid esters are used for the reaction, but also other.

- salts such as the sodium or potassium salt may be used very remarkable systemic action.

advantageously.

The compounds of the present invention are generally valuable insecticides and plant-protecting agents. They kill pests such as aphids, flies and mites and exhibit a The application of these compounds should be carried out according to the use of other known phosphor insecticides, i.e. in dilution or solution with solid or liquid carriers such as chalk, talc, bentonite, water, alcohols, liquid hydrocarbons, etc.

1 The inventive compounds may further be used in combination' with other known insecticides or pesticides, etc. Effective concentrations of the compounds may vary also;-

generally concentrations of 0.000'1% to 1.0% kill pests effectively. The combinations of the compounds may be sprayed or dusted or otherwise brought in contact with pests or plants to be'prot'ected. They may also be used as aerosols.

The utility of the inventive compounds especially has been proven by testing 0-( B-nitroethyl)-0.0-diethylthiono 1 phosphate against flies, black bean aphids and spider mites. Aqueous solutions of a concentration of 0.01 or 0.1% active ingredient have been prepared by adding the same amount of acetone to the above said active ester, then adding 50% by weight of a commercial emulsifier based on benzyl-hydroxy-diphenyl-polyglyco1 ether, and then diluting this mixture to the above said concentration. Flies are killed completely with 0.01% solutions and black bean aphids and spider mites with such ones containing 0.1% of active ingredient. I

The following examples are given by way of illustration only, without limiting the present invention thereto.

Example 1 48 grams of Q-nitroethylalcohol (B.P. 72 C.) are dissolved in 200 cc. of toluene, 42 grams of pyridine and 100 cc. of methylethyl ketone. While stirring and conducting nitrogen through the reaction tube there is added a solution of grains of diethyl phosphorus 'acid non'o- 3 cc. of diluted hydrochloric acid. The toluene layer is separated and washed once again with 50 cc. of water, then it is dried and fractionated. There are obtained 88 grams of the crude ester of the formula CzHgO s as a yellow, very little water-soluble oil (B.P. 87 C.). The oil shows a LD of 250 mg./kg. on rats orally.

By the same way but using dimethyl phosphorus acid chloride in the equivalent amount there is obtained the ester of the formula CHaO S CHaO Example 2 33 grams of B-nitroethylchloride (BB C.) are dissolved in cc. of alcohol together with 57 grams of the ammonium salt of diethylthiol phosphoric acid at a temperature of about 60 C. After a short period ammonium chloride separates. The temperature is kept at 60 C. for another half an hour, and then it is cooled to room temperature. The reaction product is poured into 100 cc. of water. The separated oil is taken up in chloroform, washed with water and dried over sodium sulfate. After removing the chloroform there are obtained 60 grams of the new ester of the formula Cal-I50 61 grams of diethyldithiophosphoric acid ammonium 'salt are dissolved in 60 cc. of methylethylketone. While stirring there are added 33 grams of fi-nitroethyl chloride. The temperature is kept at 60 C. for another half an hour and then the mixture is worke'diup as described .in the foregoing example. There are obtained 65 grams of the'crude ester of the formula l cnHsD/ which shows a LD of 250 mg./kg. on rats orally (BlR By the same'way there is obtained from the ammonium 4% salt of 0.0-dimethyldithio phosphoric acid the following compound (EH30 s CHaO Example 4 53 grams of nitroisopropyl alcohol of the formula HO(|JHCH2NO (B.P. 62 C.) are dissolved in 150 cc. of toluene together with 42 grams of pyridine. While conducting nitrogen through the reaction tube there is added a solution of grams of diethylphosphoric acid monochloride in 80 cc. of toluene at a temperature of about 30 C. The reaction is exothermic. Without further isolation of the intermediate there are added 16 grams of sulfur. The temperature then rises to C. This temperature is kept for another half an hour. Then the reaction product is poured into cc. of ice water, which contains 20 cc. of diluted hydrochloric acid. The toluene layer is separated and shaken once again with 50 cc. of water, then the layers are separated and the organic layer is dried over sodium sulfate. After removing the toluene in vacuo there are obtained 65 grams of the crude ester of the formula P-OCHOHa-NO2 C2H5O CH3 as a yellow'water soluble oil (B.P. 85 C.).

I claim: 1. A compound of the formula 0.1150 s \ll POCH3CH2NO3 CzH5O .2. A compound of the formula CzHsO O \H PSCHr-CHNO2 CiHsO 3. A compound of the formula CHaO 0 \II PSCH9CH2NO:

CHaO 4. A thiophosphoric acid ester of the formula iui 0R1 NOZ-oHZ-oEFX-P R OR? in which R and R each stand for a member selected from the group consisting of methyl and ethyl, R stands for a member selected from the group consisting of hydrogen and methyl, and X stands for a member selected from a group consisting of oxygen and sulfur, one X being sulfur and the other X being oxygen.

References Cited in the file of this patent UNITED STATES PATENTS 2,494,126 Hoegberg Jan. .10, 1950 2,908,604 Godfrey .et .al Oct. 13, 1959 2,979,522 Johnston .et al. .Apr. .11, 1961 FOREIGN PATENTS 969,440 'France Dec. 20, 1950 

1. A COMPOUND OF THE FORMULA 